Fuel System (2 Viewers)

[Vincent Jones]

My dad gave me his 76 land cruiser. It has a Chevy 350. It has 2 gas tanks. I just had both gas tanks sending units replaced and wired into one gauge. I noticed a leak. This leak was coming from a canister thing in the engine compartment. I don't know what it is but I know it is tied into the stock gas tank as it wasn't effecting the aux gas tank. Could anyone tell me 1) what it is and 2) where would the line go that is connected to the bottom of this canister thing? The line is currently missing as that is the cause of the leak. Any input would be appreciated.

 

[AntFarm]

That is an aftermarket charcoal canister that a PO used to replace your original. The bottom fitting typically vents to atmosphere. The only way to have the bottom fitting drip fuel is if your tanks are either over filled or otherwise have a plumbing arrangement that allows fuel into the canister. You will want to correct this.

 

[Vincent Jones]

When you say vent to the atmosphere is that similar to, say, a breather tube? I noticed it did it at I filled the tank. Also, I plugged it today and drove it around the block. three times it acted like it was starved for fuel. I then switched to the other tank. When I parked it, I unscrewed the plugged and a bunch of gas came out of the canister. Once it emptied it was fine. Where would that gas normally go?

 

[hobbes]

EVAP system. Hard to tell from your description what tank is doing what. Are both pressurizing? Is it only after fueling? If so, see Romer’s recent thread.

Lowering the fill point to not overfill the tank- How do I do that?

I have a 21 Gallon Fuel tank I use as my primary. The gas station pump as you know doesn't shut off until the end of the nozzle detects fuel. I think in the Man-a-Fre design that overfills the tank. FJ40 BJ40 Fuel Tank Auxiliary 21 Gallon ManAFre 1958, 1959, 1960, 1961, 1962, 1963, 1964...

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For a more general look at fuel tank pressure, here’s another recent thread…

The dreaded overpressure fuel tank!

Everyone above is correct. A previous owner did change out the fuel tank to a pre-74. Last week I removed the fuel tank, cleaned it, rust protected the exterior, and replaced all hoses. Each of the four corner vent hoses runs directly into the driver side evaporator. There is no return fuel...

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[AntFarm]

When you say vent to the atmosphere is that similar to, say, a breather tube? I noticed it did it at I filled the tank. Also, I plugged it today and drove it around the block. three times it acted like it was starved for fuel. I then switched to the other tank. When I parked it, I unscrewed the plugged and a bunch of gas came out of the canister. Once it emptied it was fine. Where would that gas normally go?

The purpose of the charcoal canister is to absorb and filter fumes from the fuel tank. By 9/77 or so it was also connected to the carb float bowl for the same purpose. It is not supposed to ever have liquid fuel in it. That’s why the OEM vapor plumbing from the fuel tank routes up in elevation into the passenger compartment before going back down and forward into the engine compartment. Lots of well intended POs over the years ripped out portions of this system as they attempted various mods. The evap system is one that IMO works the best when it’s configured per the OEM design. Get an emissions manual and study the evap section.

 

[Vincent Jones]

EVAP system. Hard to tell from your description what tank is doing what. Are both pressurizing? Is it only after fueling? If so, see Romer’s recent thread.

Lowering the fill point to not overfill the tank- How do I do that?

I have a 21 Gallon Fuel tank I use as my primary. The gas station pump as you know doesn't shut off until the end of the nozzle detects fuel. I think in the Man-a-Fre design that overfills the tank. FJ40 BJ40 Fuel Tank Auxiliary 21 Gallon ManAFre 1958, 1959, 1960, 1961, 1962, 1963, 1964...

forum.ih8mud.com

For a more general look at fuel tank pressure, here’s another recent thread…

The dreaded overpressure fuel tank!

Everyone above is correct. A previous owner did change out the fuel tank to a pre-74. Last week I removed the fuel tank, cleaned it, rust protected the exterior, and replaced all hoses. Each of the four corner vent hoses runs directly into the driver side evaporator. There is no return fuel...

forum.ih8mud.com

Its only from the front, and yes, it only happened after filling up. Both time it did it it stopped after the fuel level went down.

 

[hobbes]

Is the "front tank" OEM? Do you still have the fuel vapor separator? Should be behind a panel behind the passenger seat.

 

[Vincent Jones]

Is the "front tank" OEM? Do you still have the fuel vapor separator? Should be behind a panel behind the passenger seat.View attachment 3016792

It is the OEM and yes that separator is still there. The tube that goes into the fitting on the bottom of the cannister is not there. Once the level goes down, it doesn't leak. It was only after I filled it these last two times. The guy who put the sending unit in last month os no longer there. I think when they put the new lines in they tossed the old one. Can you tell me where that line would from the cannister? I might be able to trace it back

 

[hobbes]

The charcoal canister? As stated in post #5, there is no line that connects to the bottom of it. It is a vent line.

Below is a photo courtesy of CCOT. You should verify your fuel tank hoses are hooked up the same. No liquid fuel should be getting by the fuel separator as it sits higher than the tank. The single line out the top of the separator should run down the b pillar via a check valve, then connects to a metal line that runs to the engine compartment. From there it transitions back to a rubber line and connects to the input to the charcoal canister input.

The b pillar check valve is known to fail and cause fuel tanks to pressurize, but that doesn’t explain fuel getting by the fuel separator.

 

[Vincent Jones]

The charcoal canister? As stated in post #5, there is no line that connects to the bottom of it. It is a vent line.

Below is a photo courtesy of CCOT. You should verify your fuel tank hoses are hooked up the same. No liquid fuel should be getting by the fuel separator as it sits higher than the tank. The single line out the top of the separator should run down the b pillar via a check valve, then connects to a metal line that runs to the engine compartment. From there it transitions back to a rubber line and connects to the input to the charcoal canister input.

The b pillar check valve is known to fail and cause fuel tanks to pressurize, but that doesn’t explain fuel getting by the fuel separator.

View attachment 3016999

So there should be no fluid whatsoever in the cannister. Do you thi k the separator might be bad?

 

[hobbes]

A separator is just a plastic piece with some tubes to allow a small amount of fuel to settle out of the vapors. If the plastic cracks you will smell fuel in the cab.

You can make sure air passes freely thru it, but there shouldn’t be fluid even getting to it. It’s higher than the fuel tank for that reason.

Excessive fuel tank pressure is usually the result of a blockage in the line that connects the fuel separator and the charcoal canister. Most typically this is due to a failure of the check valve located at the bottom of the b pillar (but in my case it was a mud dauber). If the valve is bypassed and the pressure issue resolves, the valve can either be replaced or omitted.

But the entire EVAP system is designed for vapors only. I’d start with verifying all the fuel line routing as in the photo above and go from there.

 

[AntFarm]

@Vincent Jones you’re getting closer. Please go back and re-read every post in this thread, from both @hobbes and myself. Get an emissions manual and follow the EVAP diagrams. The CC should never have liquid fuel in it. You need to fix this sooner rather than later as you have a significant safety issue with this quantity of spilling fuel. We’re on your team here and we want to help you get this fixed. Aftermarket CC’s are typically fine in place of 45 year old original CCs but you might consider getting a new one at this point since yours is now fuel soaked.

 

[Vincent Jones]

@Vincent Jones you’re getting closer. Please go back and re-read every post in this thread, from both @hobbes and myself. Get an emissions manual and follow the EVAP diagrams. The CC should never have liquid fuel in it. You need to fix this sooner rather than later as you have a significant safety issue with this quantity of spilling fuel. We’re on your team here and we want to help you get this fixed. Aftermarket CC’s are typically fine in place of 45 year old original CCs but you might consider getting a new one at this point since yours is now fuel soaked.

You are probably right. Just need to find where I can purchase one. I also purchased a Haynes manual. I am hoping it covers the evap system.

 

[AntFarm]

You are probably right. Just need to find where I can purchase one. I also purchased a Haynes manual. I am hoping it covers the evap system.

I've never used a Haynes manual so I can't vouch for them. I can only speak for the factory FSM Emissions manual for your particular year. The FSM's are very good manuals, but they require some dedicated studying to learn all the systems. Since the emissions systems in Land Cruisers throughout the decade of the 70's changed every year, I recommend getting the FSM Emissions manual which is specific to your year. It will more than pay for itself in time, frustration, and money.

 

[hobbes]

Try here. Later year EVAP system if you cannot find yours.

1981 2F Engine Emission Control Repair Manual (RM36043E)

1981 2F Engine Emission Control Repair Manual (RM36043E)

content.cruisermanuals.com

Good discussion here:

Hooking up Charcoal canister and fuel seperater

The PO removed all the smog equipment including the charcoal cannister and fuel separater. Carb was swapped out for a weber. The fule tank is capped with rubber caps that disentagrate every year. I am tired of the gas in the cab and the expansion and contraction of the gas tank. I have...

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